In the existing techniques, the cause of neuromyelitis optica (NMO, also known as the Devic disease) is unclear, with most clinical manifestations of bilateral acute neuritis or retrobulbar optic neuritis as well as paraplegia caused by the myelitis simultaneously or before or after the occurrence of optic neuritis. Victims mostly suffer from acute visual acuity or complete loss of sight, and the eye-ground is shown as optic disc hyperemia and edema (the optic neuritis type) or normal eye-ground (the retrobulbar optic neuritis type).Additionally, there has not yet been with changes like torpor or loss of reflection of pupillary light reflex, huge central scotoma or centripetal narrowing of field of vision, seldom with ophthalmoplegia externa. The mortality of this disease is approximately 50%, mostly as deaths from paralysis of respiratory muscle or secondary infection in the lung or urinary system. However, current detections of this disease mostly rely on clinical diagnosis, and the accuracy rate is significantly affected by the ability of the doctor in charge.
Aquaporin-4 (AQP-4) is a member of aquaporin protein family of mediate water transmembrane transport, concentrated on the astrocytus foot process or ependymal cell surface around the brain blood capillary of central nervous system in the form of polarization. Studies show that AQP-4 extensively exists in subarachnoid space, circumvascular spongiocytes, ependymal cells and osmoreceptor organs, and it may adjust the volume of cerebrospinal fluid and cell sap. Kiening et al discover in studies that, the expression of AQP-4 at 72 hours after cerebral ischemia rises proportionally to cerebral edema, while cerebral edema is significantly alleviated in the model of AQP-4 gene knock-out mouse. The above researches and studies show that, AQP-4 plays a critical role in the adjustment of water metabolism of brain tissue, and it also participates in the outbreak of NMO. Recent studies show that, the AQP-4 autoantibody exists in the blood serum of NMO victims, while it does not exist in the blood serum of multiple sclerosis victims. After the international NMO diagnosis standard has adopted the detection of AQP-4 antibody as a core supporting condition for the diagnosis of NMO since 2006, it has highly important clinical guidance significance to the clinical early confirmed diagnosis of NMO and the differential diagnosis of other demyelinating diseases.
It is discovered in applying 15 polypeptide superimpositions of amino acid for the immunogenicity analysis of AQP-4 protein that, different peptide fragments of AQP-4 have different immunogenicities on the T-cell, among which the 22-36 amino acid inside the N-terminal intracellular domain, the 82-108/211-225/235-249 amino acid in the transmembrane domain, the extracellular 139-153 and the 289-306 amino acid inside the C-terminal intracellular domain have strong T-cell immunogenicity.
The Enzyme-linked Immunospot (ELISpot) technique established in 1983 is with high sensitivity and extensive application, currently as one of the most important detection means for immunodetection of antigenic specificity immunoreaction. This invention constructs the antigen polypeptide with specific effector T cell in combination with the features of AQP-4 antigenic structure, and utilizes the ELISpot method to diagnose the NMO disease.